1. Technical Field
Use of glass-like carbon pipes is being contemplated for a gas injection nozzle and reaction gas delivery pipe of a CVD apparatus. This invention relates to a method for producing a glass-like carbon pipe as well as a glass-like carbon pipe produced by such method.
2. Prior Art
Glass-like carbon is a carbon material, which is typically produced by carbonizing a thermosetting resin such as phenol resin or a furan resin at a high temperature. Glass-like carbon exhibits a heat resistance of 2000° C. or higher in an inert atmosphere, and it also has excellent corrosion resistance to hydrogen fluoride and fluorine. Accordingly, use of a glass-like carbon pipe is contemplated for gas injection nozzles and pipes in pipework for supplying a reaction gas to a CVD apparatus by which a thin film is deposited onto a substrate such as a silicon wafer.
When a glass-like carbon pipe of straight shape which is relatively large in length or of bent shape such as “L” shape is required, several production pathways can be considered. One is to join glass-like carbon pipe sections each configured to be a divided section of such a pipe by using adhesives. However, a product exhibiting satisfactory mechanical strength and gas sealability at the joint could never be produced by this method due to the chemical inertness of the glass-like carbon material.
The other method is to carbonize resin precursor for glass-like carbon pipe formed in such a shape. However, this method is also difficult to complete due to poor formability of thermosetting resins.
In view of such situation, Japanese Patent Application Laid-Open No. 2001-151574 proposes a method wherein sections of a resin precursor for a glass-like carbon pipe of straight shape or bent shape are first produced, and these sections are adhered and then carbonized.
In this prior art method, a cured article of plate shape is produced from a thermosetting resin, for example, by cast molding, and then recesses corresponding to the flow path and the fitting portions of the finished product are formed in the plate-shaped thermosetting resin by machining using a NC machine to thereby produce a pair of thermosetting resin cured articles corresponding pipe halves cut in the direction parallel to the longitudinal axis of the pipe. The cured thermosetting resin articles in the form of pipe halves are then adhered by using the thermosetting resin for the adhesive, and by coating such adhesive on the fitting portions. The thus adhered thermosetting resin cured articles are then carbonized to produce the glass-like carbon pipe.
However, this prior art production method of a glass-like carbon pipe has a drawback of prolonged working time for the machining, and hence, increased production cost since this method involved the step of machining of the brittle plate-shaped thermosetting resin cured product into the required shape using a NC machine or the like, and the machining of the brittle article was associated with the problem of poor workability.
Furthermore, a thermosetting resin cured article often experiences a decrease in the adhesion due to the reduced reactivity of the thermosetting resin when the article is cured to the extent that allows machining. Such reduced adhesion capability resulted in the drawback of difficulty in producing a product having satisfactory mechanical strength and gas sealability at the joint.